Optimizing generalized transfers between storage systems including identifying, by a first storage system, a request to transfer source data from the first storage system to a second storage system, wherein the first storage system implements a first storage architecture and the second storage system implements a second storage architecture; identifying difference information between the source data that is stored on the first storage system using the first storage architecture and existing data that is stored on the second storage system using the second storage architecture; and transferring, in dependence upon the difference information, a subset of the source data from the first storage system to the second storage system.